chrismcdude said:
parallel said:
I don't think that drone footage from a cloudless sky with reflective snow cover beneath and still recognizable as a quadcopter, comes nowhere near the circular halo light filmed in Brazilian cloud covered dusk.
Hmm. You're right. It cannot be due to reflection alone, considering that the sky seems to be pretty dark at the time the video was shot.
Tigersoap said:
Here is a video of a Phantom DJI at night to compare.
_http://www.youtube.com/watch?v=SbfPkxz30_4
Not sure it clears it all up.
This video does a better job of explaining the drone's strange "glow".
Tigersoap said:
The Phantom DJI has a limited control distance, it seems to fly higher up in the protest video ?
I can't really estimate the distance though.
The 2.4 G ISM frequency makes the effective control distance up to 300 meters (can be impacted by the specific flight environment)
Product page :
_http://www.dji-innovations.com/feature/phantom-features/
That would make the official
control distance upto around 1000ft max. In one of the reviews for this quadcopter listed on Amazon's website (here : http://www.amazon.com/DJI-Phantom-Aerial-Drone-Quadcopter/product-reviews/B00AGOSQI8), there's the following
ADDENDUM: Quick note, but I was dead wrong about the maximum altitude the Phantom can achieve. On my second flight, it just kept climbing as it disappeared into the clouds. I lost visual, and was sure I'd never see my Phantom again. I didn't notice the the throttle stick does not revert to center when you let it go. It stays where you leave it, and for me, that was full throttle. From calculations based from DJI's web site that it climbs 6m/second, which means it attained an altitude how somewhere between 5000 and 7000 feet. I didn't realize until I got the video back. This is *not* good, though, since untiI I saw the video, I didn't realize I was in controlled airspace. Do *not* do this. Keep you Phantom in visual range at all time, or risk getting arrested, or even worse, causing a flight accident. You should not fly it at over 400-500 feet.
Now I know this guy has not used an altimeter and is making this claim based on his calculations, but assuming the lowest clouds to be at a height of <6500 ft (the clouds in the video look like Cumlus/Stratus/Stratocumulus, http://nenes.eas.gatech.edu/Cloud/Clouds.pdf), the drone may be able to make it up to the low-level clouds.
Even then, the video is of pretty low quality and I am not really sure if the quadcopter actually does fly into the clouds. It just seems to be moving away at an increased altitude but at that distance, and due to the video's low quality, it may give the impression that it's flying up into the clouds.
I think you are right about the drone being able to enter the clouds.
Regarding the 2.4 GHz, I think it can communicate a lot further than 300m. I had a number of model sailplane gliders and now they are flown using 2.4GHz systems and they keep being flown in and out of clouds, probably much higher than the clouds seen in the video.
The supposed UFO seem to me to be at least partially engulfed by the clouds at around 0:44~0:46 if you see it frame by frame (_https://www.youtube.com/watch?v=X6hDQB_WG8w). So I was trying to figure out the cloud altitude with some accuracy.
I was able to obtain from _http://bancodedados.cptec.inpe.br the Synop and Metar meteorological data for June 20, 2013, São Paulo. There are three Synop and two Metar stations that are closest to Paulista Av, where the video apparently was shot. These stations reported the following information for 18:00 on that day :
Air temperature (ºC): 22.7; 22.0; 20.7
Air relative humidity (%): 61; 69; 72
Dew point temperature (ºC): 14.9; 16.1; 15.5
Cloud base of lowest cloud (meters above ground): 2250; 450; 800
Since the cloud base of lowest cloud seen was very different between the three Synop stations, I thought that maybe the 450m and 800m measures indicate low cumulus clouds and the 2250m measurement could indicate a moment where there were no low cumulus directly above the station and it was measuring a higher level of clouds. The average of the three would be 1166m.
Given the difference I calculated the cloud base based on an approximation for cumulus clouds that I found online ((air temp - dew point temp ) x 120). This would result in 936m, 708m and 624m. The average would be 756m.
So, it seems that the cloud base was indeed low that day (I think anything below 2000m considered is low), maybe between ~750m and ~1200m but probably not exceeding 2250m, which was actually measured. This would be very close to or even lower than your estimate of 6500ft (1980m).
Nevertheless, the strong light seen in the video is very weird and strong. Also, maybe we should be able to see some faint "cone" of light if the idea of the LED is to illuminate what is being filmed? Or maybe there is and the resolution doesn't allow us to see it. Or maybe it was just videoshoped, as suggested by Perceval.